Internal-combustion engine of oscillating piston type



Jan. `9, 1945.

M. M. BLU FSTON INTERNAL-COMBUSTION ENGINE OF OSCILLATING PISTON TYPE Filed` July s, 1942 5 sheets-sheet 1 Jan. 9, 1945. M, M BLUFSTQNv A 2,366,996

ITERNAL-COMBUSTION ENGINE OF OSCILLATING PISTON TYPE AFiled July s, 1942 v 5 sheets-'sheet 2 AINVE/v-TOR;

f4 TTOHNE Y Jan. 9, 1945.' M. M. BLuFsToN 2,356,996

INTERNAL-COMBUSTION ENGINE OB OSCILLATING PISTON TYPE Filed July 3, 1942 5 Sheets-Sheet 5 WMe/.V17

ArraR/VEY Jan. 9, 17945'. NLM, BLUFSTON 2,366,996

INTERNAL-COMBUSTION ENGNE oF oscILLATING PIsToN TYPE Filed July 3, 1942 5 Sheets-Sheet 4 V 26 73 HI f/ Jan.'9, 1945. M, M. BLUFsroN 2,365,996

INTERNAL-COMBUSTION ENGINE oF oscILLATING PI'sToN TYPE Filed July 3, 1942 5 Sheets-Sheet 5 MART/N M. B1. UFS TON www? l A TTOF/VEY Patented Jan. 9, 1945 UNITED STATES. PAT ENT oFF-ICE l INTERNAL-C'MBUSTION ENGINE OF OSCILLATING PISTON TYPE This invention relatesl tol internal combustion engines of oscillating piston type, and has particular reference to a multi-cylinder engine of this character, having the several cylinder units and wherein novel'and effective `gearing is employed to operatively connect the oscillatingpistons to the engine shaft.

The principal object of the invention resides in ,the provision of an engine of the character indi- Lcated, wherein the power impulses of the cylin.

der units are imparted to the engine shaft by novel gear mechanism, thusy avoiding heavy reciprocating parts common to engines of reciprocating' piston type, and further wherein the improved arrangement includes cylinder units related in diametrically opposed pairs about vthe engine shaft, and according to one embodiment of the invention, separate gearing operatively connecting the oscillating pistons of each cylinder pair to the engine shaft. According `to another embodiment of the invention, the novel gearing interconnecting the engine shaft and the several oscillating pistons, includes a single driven gear common to all of the cylinder units.v

Another object is to provide afnovel and effective gear drive mechanism between the oscillating pistons and the engine power shaft, for a multi-cylinder engine of the character indicated, wherein each of the cylinder units includes cooperating oscillating pistons or vanes operable about separate axes and oscillatable through a relatively wide angle, as of the order of 180 degrees, and wherein the pistons of each unit are Fig. l, but at the opposite end of the engine, with portions of the engine shown in section to illustrate the oscillatingpistons inthe cylinder units; Fig. 4 is a sectional view transversely through one of the cylinder units, 4as taken from the line 4 4 in Fig. l;

' arranged radially about the engine power shaft,y

Fig.r 6 is an enlarged fragmentary view of the novel gear mechanism as employed to interconnect the oscillating pistons of each cylinder unit to the engine shaft;

Figs. 7 and 8 illustrate in side and end elevations respectively, the form and gear mounting arrangement of the lead tooth in each gear sector of the gears on the engine shaft;

Fig. 9 discloses somewhat diagrammatically, a

modication in thel piston drive arrangement adapted for use with cylinder units wherein'the y pistons oscillate about axes having a minimum relative spacing, and i Fig. 10 illustrates diagrammatically, a modified piston-engine shaft drive mechanism effected according to the present invention.

Referring to the drawings by suitable characters of reference, the numeral IIJ designates generally, a preferred form of engine of the type indicated, having embodied therein the featuresof the present invention. According to the exemplary disclosure, the engine 'includes four cylin- Fig 5 is a diagrammatic view of the engine inv end elevation, illustrating thefuel and exhaust Vder units II, l2, I4 Vand I5 which are arranged radially about and equally spaced from a central engine power shaft I6, each of these cylinder- `units by preference, being of four-cycle, doubleacting character. The cylinder arrangement further is such that-the units Hand I2 are diametrically opposed, while the remaining units I4 and I5 are similarly related but displaced lrelative to the iirst pair by a quarter-turn or degrees, as clearly appears in the drawings. lAn engine frame of any suitable construction jis provided for supporting the cylinder units and engine shaft, and as herein shown by way of example only, such frame may include a central member l1 Fig.'4 iongiiudinaiiy bored io receive and journal therein the engine shaft I6, an engine mounting base I8 (Fig. 2) at one end'of member I'I; and cylinder supporting means as i indicated in broken outline at I9 in Fig. land .shown in part by the member Ia, in Fig. 4.'

Apart from the piston drive connections to the engine shaft I6, vthe several cylinder -units are Videntical in construction, hence a description of complementary cylinder shells 20 having external flanges 22 about the mating shell margins L23, through Which the' shells are secured in as- AWall surfaces. form, the-cylinderwall surfaces in the opposite `end -zones .f342and .35 through which the krespecsa.:

felemen-t 5150 on *a `cam shaft :52. .valve"53 `controlstthe'.exhaustport 4'1, and has r' a' stem t 54 .projectingjexteriorly of thecylinder for :actuationbyyan exhaust1cam^55 oncamshaft52. 1 :Eachfofthe valves' is urgedltoward port-closing @position by 2a suitableyalve biasing spring 56. `Bearingarms 151 -on thencylinderi-shells 20proyide-the-operative.support for the camshafts 52. `Asshown'by Fig. 4,v the `camshaft 52. nearest the i.

sembly as by bolting 24. A gasket indicated at 25, may be employed at the flange joint to effect a gas tight assembly. Arranged Within the cylinder are a pair of pistons or vanes 26 and 21 which are oscillatable about separate, spaced axes, as the respective piston shafts 28 and 29 to which the associated pistons are secured. The cylinder which by preference is divided in the plane of the Apiston axes, has each-of the shellhalves formed'toiprovidehalf-circular bearing seats 30 and 32 in the opposite portions 33 of the shell margin 23, 'the seats 30 cooperating in the cylinder assembly, to operatively journal the piston shaft 28, while the seats-32 'cooperate similarly to journal the other piston shaft v2'9. The piston shafts are projected outwardly beyond one side of the cylinder for driving connection to the engine shaft I 6, as Willbehereinafter fully described. y

Each of the pistons 26 and 21 is by preference.

semi-circular in peripheral extent, `to :facilitate its operative packing with respect to the cylinder To accommodate pistons of this tive pistons 26 vand 21 oscillate,"aresemi-spherical. Accordingto this arrangement, each pisvton:isthusfadaptedfor oscillation through a full lhalf-turn or'fa`180 degree-arc, aswill be observed in particular from=the viewiof Fig, 3. While any FI suitable pistonlpacking means'mayfbe employed` 'in the present example :each piston is provided lwith" a `groove-136 1in1its peripheral surface, to f receive a half -circular packing ring` `31 of' suitable sealing material, and this ring maybe biased into sealing contact lwith the cylinder surface by -springsin the groove beneath the'ringone such spring being shown -at38 (Fig. 3)` in each piston.

JA- cylinder partition :39 between the'piston'shafts T28 and v 29andsuitablyirigidlyfsupported by oney of the cylinder shells20, cooperateswith kthe pis- 'With particular-reference itoFig. :4,the cylinder unit Whichrby.preferenceisdadapted forfour- `cycle operatiomhas the centralportion 43ofea'ch lcylinder shell --ZIII'somevvhat thickened or internally bossedias shown,.and.forme'd in the portion `43 are fuel inlet and `uexhaust ypassages r`44 and l45 respectively, terminating in respective port op'enings-4'6fand `l`41 communicating with oneof the combustion chambers .40 `and 4l.

A `valve 48 controls vthe fuel inlet port 46, and includes fanactuating stem :46 .lextending to the eX- Iteriorof the cylinder'for actuation Yby -a vcam 'Similarly, a

engine shaft I6, is driven therefrom by a gear 58 secured to -the latter, enmeshing a pinion 59 on one end of the camshaft, the gear-ratio of the gear-pinion connection being selected so as to effect proper timing of valve operation by the cams 50 and 55, as for four-cycle operation of the engine. The opposite camshaft 52 may be driven synchronously With the camshaft 52 driven from the engine shaft I6, by an interconnecting drive of bevel gear-type, -as illustrated. Con- .nected to each of the fuel passages 44 is one end portion 62 of a fuel conduit 63, While similarly connected to each of the cylinder exhaust passages 45is .one end 64 of an exhaust discharge conduit-65, the fuel and exhaust conduit system for .the entire engine being shown diagrammatically in Fig. 5. Ignition of the fuel charges in the cylinderfmay be effected by the usual igniting devices, such as a spark plug 66 (Fig. 4) associated With each of the cylinder combustion ychambers 40 and 4I.

rIt is to be observedthat the cylinder bosses 43 `which contain the valve ports and passages as above described, serve to reduce the initial volume-0f the combustion chambers to a desirable extent, such .that highercompression and combustion pressures may be thereby attained. The initial volume reducing function thereof is clearly illustrated in Fig. 3- in respect to the cylinder unit II at the topzof thefigure. In this connection, it may be noted here that thecylinder partition 39 may be considerably increased in thickf ness to effect a further decrease in' the initial vcombustion space volume, or the partition 39 of suitablethickness, may be relied on entirely for thispurpose, with the internal projection of the bosses 43 reducedv toa minimum.

With reference now to Fig. 5, this'view illustratesdiagrammatically, a suitable fuel and exhaust conduitsystem'for the 'several engine cylinder units, as Well asthe common drive arrangement for the camshafts of the units. As there shown, thecylinder units 'I land I4'are supplied with fuel from .a carburetor assembly 61 of any suitable or well-known form, feeding fuel charges to the cylinder fuel passages'through the branch conduits63. Theremainingcylinderunits I2 and I5 are supplied in Alike manner through branch conduitsv63from-a carburetor A`assembly 68. The

Vexhaust gases from thecylinder units II and I5 are conducted through the exhaust conduit branches to amanifold duct 69 leading to a `point of exhaust discharge, whilethe other cylin- .der units I2 and I4 .exhaust through like branch `conduits Av65 `and .a manifold duct 10.

With respect to the valve camshaft system, it Will appear that .the gear v58 on engineshaft' I6 serves as a common drive for the inner or adjacent camshafts 52 of the cylinder units, as through the camshaft pinions`59. Operation of the more re- 'mote camshaft 52 in each cylinder unit, is effected from the inner camshaft by a suitable drive 6I), as hereinbefore indicated. Thus from this diagrammatic view, and from the structural views of Figs. 1, 2 and 3, it will appear that a relatively compact assembly is 'effected with a desirable symmetrical arrangement'of the engine cylinders and described adjunctive parts, about 'the engine power shaftIB.

Turning now to the novel gear mechanism for `interconnecting the pistons and engine shaft so as to translate the oscillating'movements of the former to a continuous unidirectional rotary move- :ment of the latter, reference is directed to the disv closurethereof in Figsrl, 2 and 6. Describingrst Y the-operative connection of thediametrically opposed lpair of cylinder unitsmll and l2 .to the engine shaft Hfleach ofthese units has a pinion 12 keyed or otherwise secured on the projecting endof the piston -shaft 28, and a like pinion 13I vsimilarly secured on the projecting end of the other rp'iston shaft 28. As appearsfrom Fig.l 2 inpartiqular, the pinions 12 and *13 which are 'relatively wide, are axially offset substantially to the'extent of one-half the widthof each, and the aligned portions thereof vare in full engagement as shown inFig. 1. 'The tooth formand enmeshing relationship"thereofis, by preference, such `as to minimize or substantially preclude any lostl motionforV back-lash r movement ofV the l pinions; i

whereby to assure equal and synchronous Aoscil-r g lating movements of thel pistons 26 and 21.

- According to the present invention, unidirectional rotation ofthe engine shaft I6, say in the v clockwisev direction as viewed from Fig. 1, isA atf tained from the oscillatory movements of the vpistons 26 and 21, softhat in the present example,

f only the counterclockwise movements of the pinl ions 12 and 13 are utilized tovdrive the shaft.' To Y this end, a gear'14 suitably secured to engine shaft l S, is arranged thereon so as to be disposed y in a plane to one side of the plane of engagement of 'pinions 'l2-and 13, for engagement solely-'with the free portion of the pinion 12. AThe gear 14 pas shown by Fig. l1 is of incomplete or mutilated characten'to provide as in the present example,

j yf'ourequally spaced tooth sectors 15, the gear thus being adapted for intermittent engagement with pinion'12. Alike incomplete gear 16 is similarly securedto the shaft I6, and is positioned toene` side ofthe plane vof pinion engagement for intery mittent engagement of its tooth sectors 11 solely with the free portion of 'pinion-13.y The` pinions v12 yand 13 oscillate through a half-turn, since in y f the 'present example, the piston vanes 2B and 21 l oscillate through 180 degrees, and hence the present gear-pinion arrangement is such that during the counterelockwise half-turn of each pinion (las vviewed in Fig. 1), itengages oney of the tooth #sectors-on the associated gear todrivethe gear and engine shaft in the clockwise direction.I

The gear 14 -being provided with four equally spaced `tooth sectors 15 as presently preferred, has each sector formed -Within an aro of 45 degrees at the gear periphery, the sectors in each case having a plurality of teeth less in. number than one-,half the'number of teeth on the associated' i bled to the gear 14 so as to be retractible in ref sponse to abutment by the pinion tooth 80. Ac-

i of the gear.

cordingly, and as illustrated by Figs. 7 and 8, y `the tooth 18 has'its forward face 82 inclined toward the blank periphery 83 of the gear, and-is received in a gear pocket or recess 84, for pivotal movement about a pin 85 arranged transversely Inwardly opposed flanges 86 at the outer end of the recess 84 cooperate 'with projecting flanges 81 at the base ofthe tooth 18 to limit the outward extension of the tooth, while a suitable spring 88 in the bottom of the` recess 84 and bearing against the tooth', serves to urge the tooth outwardly of its recess. As will be now observed,

the pinion tooth 80 in moving clockwise over thev gear tooth 18, willengage the inclined surface 82v of the latter, to cam `the tooth downwardly in its recess 84. When the pinion tooth -80- clears the tooth 18, the gear tooth under the influence of its spring 88', will immediately pivot upwardly as by' a snap-movement, into position Ifor driven engagement withy the pinion tooth. The tension of spring 88 is selected so that it will eiectively oppose any retraction of tooth 18 upon driving contact'of pinion tooth 88 with the gear tooth. The lead tooth 18 of each of the gear vsectors y15 on gear 14 is thus adapted for retracting movement, to assure a positive driven engage- -ment thereof with the pinion tooth 8) when the latter 'is reversed tol rotate counter-clockwise. For the same reason, the lead tooth 89 of each gear sector 11 on gear 1S, is similarly constructed' for retracting displacement in its operative associationwith the pinion 13.

As will be observedfrom Figs. 1 and 2, 14 and 16 are relatively angularly displaced such that the sectors 11 of gear 15 lag the sectors 15 of gea/r 14 by a predetermined degree, this provision being eiected together with the formation of each of the lgear sectors 15 and 11 within an arcuate extent of degrees and each with less than one-half the number of teeth on the Aassociated pinion, so that during clockwise rota,- tion of the gears, the pinion 13 rotating clockwise while pinion 12 rotates countercloclowise, will be free of' engagement with a sector .11,on gear', while the pinion 12 enmeshes a sector 15 on gear` 74. Conversely, this arrangement serves to, free pinion 212` from the gear 14 while the pinion 13 `rotating counterclockwise, is in driving engagement with a sector 11 on gear 16. f

In the operation of the drive connection thus far described, and lconsidering for the present the cylinder'un'it Il in Fig. 1, wherein the pistons 28 k and-'21 are in their upper extreme positions as indicated, the gear 14 is initially related to the 'pinion 12- such that thefleadng tooth 18 of one ofthe gear'sectors 15 has its rear face 19'oDiJOsed to and substantially in vcontact with* the pinion tooth 80, as clearly shown in Fig. l. Now upon firing of a fuel charge in the combustion chamberbetween the pistons 26 and 21, the pis- 180i one gear sector 15 has the upper portion of its rear face 19 positioned for immediatev engagement by a tooth 8D on pinion 12, this upon counter-clockwise rotation lof the pinionv infresponse to reversed or counter-clockwise moveiment of the vane 26,

Since justprior to the .attainmentof the -indicated gear-pinion relation, i the pinion was rotating oppositely to the clockwise rotation of rthegear 14, the pinion tooth 80 f f must ,move over the gear sector lead tooth 1B 7to the position shown. In order to` eiect this. re- V *sultLthe lead tooth 18 isconstructed and assem.

tation. of gear. 14 through the sector 15 theretons will be thereby rotatably displaced to the opposite extremey of. their pivotal or oscillatory movement, to produce countercloclawise rotation of pinion v12 and a corresponding clockwise rotation of the pinion 13. The counterclockwise rotation ,ofv pinion 12 thus will eiiect` a clockwise roof -in engagement with pinion 12, and rhence a corresponding rotation of engine shaft i6. .Dur-

, ing the above described drive of the gear 14 by pinion 12, thecornpanion pinion 13 idlesy with respect to its, associated gear 18, this beingy permittedby the lag arrangement of the seotors11 the gears,

.von ,gear'16 relative to .theisectors 15 on gear 3.14,

wherein theangular extent :of thelag is `predertermined fora given gear assembly, so thaten' gagement .between a sector 11 'and pinion .13 can- :not'occurwhile the pinion is rotating clockwise.

Conversely, the lead thus provided for the sectors of gear V14, serves similarly to prevent engagement of a sector 15 with pinion 12 While it is rotating clockwise during counterclockwise rotation of pinion 13 in driving engagement with a sector'11 on gear 16. The foregoing result is assured by forming the tooth sectors 15 and 11 suclrthat each covers less than an `arc of45-de .grecs at the gear periphery, yto an extent such lthat forexarnple, when ,the lead tooth of a sector ongear 14 `attains adrivcn engagement with the .actuating pinion 12, the last or trailing tooth of the adjacent sector 11 ron gear -16 (which has been .in driven engagement with the pinion 13)` is free ofthe pinion 13.

With reference to Fig. 6 which presents an example of the foregoing conditions of gear-,pinion operation, the gears 14-16 and pinions 12-13 are shown in an'operative relation existing when Ythe pistons 26 and 21 fully attain their lower eX- treme po-sitions in cylinder unit I I (opposite to the positions thereof indicated in dotted`outline `in Fig. 1). As there shown, the leadingtooth 89 of one sector 11 on gear 1B is in position to be en- ,gaged by a tooth 90 on pinion 13, upon counterclockwise rotation of the pinion. At the same time, the trailing tooth 92 of the adjacent ysector 15 on gear 14, has its rear or trailing face substantially clear of contact with the nearesttooth 93 on `pinion 12. Now upon reversal of piston movement, as to produce counterclockwise rotation of pinion 13 and ,clockwise rotation of pinion 12, pinion 13 will engage the sector 11 of gear 16 to drive Lthe gear and hence the engine shaft in the clock- 'wise direction. As this occurs and since gear 14 moves with gear 16, the trailing tooth 92 on sector 15 of the gear 14 wil1 be displaced clockwiseawal7 from the Zone of tooth 93 on pinion 12, so that pinion 12 which is now rotated clockwise, and the sector of gear 14 are fully disengaged. The pinion 12 thus idles with respect to its gear 14. As `the pinion 13 continues in its counterclockwise half-turn, it drives the engine shaft through the sector 11 of gear 16 engaged thereby. However,

sincethe sector 11 has fewer teeth than one-half the number on pinion 13, and further, is formed over less than a 45 degree arc at the gear periphery as before indicated, the pinion will not drive the gear 16 through a full angular extent of 45 degrees or one-eighth of a turn, as is required to Thus in order to complete rotation of gear 16 and hence the gear 14, to bring the lead tooth 18 of a sector 15 on gear 14 into driven engagement with ltooth 80 on pinion 12, the cylinder units I4 and I5 are arranged so that one pinion of each is in full driving engagement with one gear of the set associated with these units as the pinion 13 approaches the end of its counterclockwise rotation.

The units I4 and I5 and the operative connection thereof'lto the engine shaft I6 will'be presently i described.

The `.foregoing .described-cycle of piniongear engagement .is continuous throughout engineop- -eration,.so that the oscillationsof thepistonsl :and 2-1 are thereby translated to unidirectional rotation of the-engineshaft I6. .Moreoven the ,cylinder .unit yi2 indiametrical .opposition to unit II, :operates the gears 14 arid I6 exactly `as 'described for the latter unit, so that vthese cylinder units have a common operative connection .tothe `shaft I6. Also, the firing cycles of the units II yand I2 .are by preference, synchronized, in order to balance .the torque applied therebyto `the gears 14. and 16, as this will be appreciated.

The cylinder units fI-ll and i5 each having enmeshingpiston pinionslfand IOI corresponding Ato pinions 12 and 13, are operatively connected to shaftlby aset oincomplete gears |02 and |03 secured to the shaft, these gears in form and operative relation vto the pinions |00 land I0 I, being identical with the-gears 14 and 16. Although the pistons of the units I4 4and I5 may be positioned -so asto have any desired, but appreciable out-ofphase relationship with the pistonsof the units II and I2, according to the present exemplary disclosure, they are displaced `relative vto the latter ypistons soas to effect a 90 Idegree out-of-phase relationship therewith, as this is-clearly shown-by Fig. 3. The eifectof such phase relationship between the paired cylinder units is to assure atall times, anoperative engagement of the `pinions of one pairof cylinder units with theassociated engine shaftgears, asfor the purpose heretofore in- 'dicated Also, the firing cycles of the units vI4 and I5 are out-of-phase with such cycles of the `units II and |2preferably by a corresponding .degree, this being effected in order toobtain a desirable spread `of the power impulses transmitted Yto the engine shaft in each four-cycle operationof the cylinders. It is to-be noted additionally, that the `four gears 14, 16, |02 and |03 function collectivelyas a flywheel, to render smoother engineoperation according to the usualfunction of such element.

.A modified piston-engine shaft drive connection is illustrated somewhat diagrammatically Vby Fig. 9, thisdrive being adapted for -use withlcylinder units of the form and construction herein described, wherein the relative spacing of the vpiston shafts 28 and 29 is considerably reduced` over the spacing thereof shown by Figs. 1 and v3. One result of so limiting the yspacing-of the piston axes is to effect a small or minimum initial volume of the .combustionchamber between the pistons 26 and 21-when in eitherof their oppositeextremes of oscillating movement, and hence to produce thereby higher compression and combustion pressures in vthe cylinder unit. With refer- `ence to Fig. 9, pinions |05 and It are secured respectively to the projecting ends of the piston shafts 28 and 29. A stub shaft |01 supported by a frame member |08, has a pinion |09 on one end of the shaft arranged for constant mesh with the pinion |05, and has secured to its opposite end a larger `pinion `I I0. Similarly, a second stub shaft I I2 on frame member |08, is provided with a pin- ;ion I I3 in mesh with the pinion |06, and a larger pinion II4 in constant mesh with the pinion IIO. The pinions |05,I06, |09 and I'I3 are identical, so as to effect a unit ratio of drive between the piston shafts .2 8-29 and the stub shafts I01-I I2, while the larger pinionsl I I0 and I I4 preferably are identical in character to the pinions 12 and 13 heretofore described. The incomplete gears I I5 and I I6 onengine Ashaft :|6, arranged for driven engagerment with the .pinions ||0 and I|4 respectively,

corre'spond in form andrelatively displacedposition tothe gears 11|,l and 1,6 associated With'pinions 1 2 and 13, the vonly difference being that the gear i ||6 associated with pinion 4 leads the gear v| l5 asis obviouslynecessary in this modified drive.

It will be appreciated that by lengthening the main engine shaft |6, one ormoreadditionalcylinder organizations of the character and arrangeapplied to the engineshaft in each revolution thereof. Y

shaft drive arrangement fofa further modied character, there are provided Va pair of cylinder units |20 and |2| in diametral opposition relative to engine shaft |22, and a like pair of cylinder units |23 and |24 also in diametral opposition with respect to theshaft |22, the latter pair however rbeing angularly shifted relative to the first pair by, anV angular Vextent' amounting to less-*than 90 degrees, this for ya'purpose which willappear presently.` Apart from the vdrive assembly,thesecylinder units may correspond in all respects with the exception of the relative spacing ofthey piston shafts, tothe units |2`, 4 andr i heretofore described. Projecting from the cylinder casing of unit |20, are the ends ofthel pistonshafts |25` andk |26, and secured onthes'e shafts ends are like pinions |21 and |28 which are in constant mesh in order toy maintain synchronous .oscillation .of the piston |29 and |30, the latter being shown in outline only as positioned in their upper extremefof oscillating movement within thecylinder. These pistons are shown relatively yclosely spaced, as in the embodiment illustrated by Fig. ,9,pwhichir .thereby attains a desirable minimum initial combustion` space between the pistons. l

Supportedby a frame portion |32 of the engine frame (not shown), are spaced stub shafts |33 and |34, each equidistant radially from the engine shaftv |22. lCarried by the stub shaft |33 is a pinion 35, which enmeshes the piston pinion |21, While a'somewhat larger pinion 36 is likewise arranged on the shaft. The pinions |35 and |35 may be separate elements suitably 'secured together vor to the stub shaft for conjoint rotation, or as presently preferred, these may-'be formed as a unitary double-pinion structure, in which case it may be freely rotatable on the stub shaft with the latter /hxed in the frame |32. A like unitary pinion assembly is supported by the other stub shaft |34,.to provide a pinion |31 in mesh with the ypiston pinion |28, and a larger pinion |38. i

Accordingvto the 'modified embodiment, the

large pinions |36 and |38are disposed in a cornmon plane normal to the engine shaft |22, for alternate drivingvengagement with a single incomplete or mutilated gear |39 secured upon the shaft |22. 'The gear |39 is formed to provide as in the present example, four equally spaced tooth l5 With reference now` to Fig. 10 which illustrates y somewhat diagrammatically, a piston-engine driven engagement thereof with the pinions |33 and |38, and for present purposes, the construction iof each lead tooth may be similar to that provided for the lead teeth 18 on thegear 14,

as heretofore described and illustrated by Figs.

1 and 8. v

With the gear |39 and piston-pinion assembly of cylinder unit |20 related as shown in Fig. 10, as the pistons |29and |30 approach and attain their upper or top dead-center positions shown in broken lines, the right-hand large pinion |38 driven through the pinion set I28-|31, attains one extreme of its rotary movement, following clockwise. rotation thereof. At the same time the gear Y|39 rotating clockwise assumes the position shown, wherein the'lead tooth |42 of one 'l gear sector |40 is in engagement with a tooth |43 on pinion |38, this being permitted by reason of the retractible nature of the leadtooth which allows the toothv to be displaced by the pinion tooth `|43 as the latter moves over the gear tooth. The left hand pinion |36 in rotating counterclockwise (through the pinion set |21|35 and piston |29 in moving outwardly to its outer extremeposition as shown), has been in full driving engagement with the particular gearsector above indicated, and in the position of the parts 'shown in Fig. 10 which obtains at the instant of reversal of pinion |36, a pinion tooth |44 has its tip substantially in contact withthe opposed tip of the trailing tooth` |45 of erably oscillate through'a half-turn or 180 de- Y' the gear sector. Thus the gear sector shown is between 'and in contact with the driving pinions |36 and |38. Now upon reversal of the pistons |29 and |30, the pinion |38 will be caused to rotate counterclockwise to engage the sector |40 and driveA the gear and engine shaft in the clockwise direction, while the pinion |36 is thereby rotated in the clockwise direction in an idling manner, since it is free of tooth engagement with anysector on gear 39. This last results from the fact that the gear sector |40 in moving clockwise, has its trailing tooth |45 displaced away from thev pinion so that tooth interference cannot occur.v

n Following reversal of the pistons |29 and |30, the'pinion 38 drives the gear |39 through the sector |40 thereof, until the pistons reach the opposite or inner extremev ofk their oscillatory movement. vAt such time, the pinion |38 and gear sector |40 will be related exactly as 'above described for the pinion |36 and sector |40 as'shown in Fig. 10, so that the trailing tooth 45 of the sector has its trailing tip'in contact with the tip of the adjacentvtooth on the pinion. Since according to the present example, the pistons prefgrees, the' pinion 38 'mustlrotate through an angle greater thanv degrees in order to actuate the gear sector |40, engaged thereby, from the initial position illustrated in Fig. l0 to a position as above described. Hence to attain this result, the gear ratio of the meshing pinions |28- |31' is selected so as to provide for the necessary greaterrotation of the pinion |38. A like sectors |40 wherein each sectorisconiined vto an. l

a retractible character in order to effect initial.y

gear ratio is effected for the pinion set |21|35 to produce greater than 180-degree movement of the drive pinion |36, since the latter in each counterclockwise rotation thereof actuates the gear |33 through one of its sectors |40, exactly as described for* the pinion 38.

Each of the remaining cylinder units |2I, |23

yand |24 has a gear-actuating pinion assembly which is 'substantially identical to that herein- |39 in each counterclockwise rotation of the corresponding pinions |36|38 thereof, while the units |23 and |24 also in diametral opposition, are similarly related for conjoint actuation of gear. |39. The latter units however, are displaced or angularly offset from the paired units |-l2l by less than 9,0 degrees, as clearly illustrated in Fig. 10, this arrangement being effected in order` toassurea full driving engagement between these units and the gear. |39 when one or the other `corresponding pair of drive ypinions |36-,-|,38 of units |2|l|2| have completed their drive engagement with the gear, and conversely with-respect to the units |23 and |24.

The modiiied drive assembly asnow described, provides but a single driven gear |39 common to all of the cylinder units, and the arrangement is such that one pair of cylinder units is in full driving association with the gear at any given time. It is to benoted that the gear |39 mayr Well serve as a flywheel to` effect smooth engine. operation, while, the firing order of the doubleacting cylinder units may be selectedso as to produce relatively evenly distributed power im. pulses with respect tothe gear |39. Also, it will be readily appreciated that more than one cylin, der and engine shaftdrive organization as illus. trated by Fig. 10, may be related to a common engine shaft to effect engines of varying capacities. Thus the present improvements are particularly advantageous tothe manufacturer of unit-type engineswherein engine units may be added or removed as desired.

While the present description relates princi. pally topreferred embodiments of the invention as herein illustrated, Iit will be appreciated that alterations and further modications may be effected without departing from the spirit and full intended scope of the invention, as defined bythe appended claims.

I claim:` v

1. A mechanism of the character described adapted for an internal combustion engine of, oscillating piston type andvofa character providf ing apair of oppositely oscillating pistons in a cylinder, and an engine shaft spaced therefrom,

the mechanism being provided for translating the oscillating movements of the pistons to a unidirectional rotary movement of the engine shaft, and including a pair of pinions arrangedv for synchronous and opposite oscillation from they oscillating engine pistons, the pinions further be, ing arranged such that their oscillation axes are relatively angularly spaced about the engine shaft axis as a center, by substantially less than a right angle, and gear means provided for mounting on the engine shaft for shaft-rotating coaction with said pinions, said gear means being of mutilated gear-tooth character Iproviding spaced sets of gear teeth, adapted for a1- ternate driven engagement with said pinions a plurality ofl times in each complete revolutionv of the gear means, the sets of gear teeth on said gear means each having the lead tooth thereof formed separately of the gear means, and means mounting each lead tooth on the gear means to permit tooth-retraction inwardly of the gear periphery, asfor the purposedescribed.

' 2.- A-|A mechanism of the character describedv 'Il adapted :for-v an internalv combustion engine of oscillating piston type -andof afcharacter providing a pair ofoppositely'oscillating pistons in a cylinder, and an engine shaft spaced there from, the mechanism being provided forl translatingthe oscillatingv movements of the engine pistons to a continuous, unidirectional rotary movement 'of the engine shaft, and comprising a pairwo pinionsY each oscillatable by one of the engine pistons, and arranged in lapped engagement such that a portion of each pinion is free of tooth engagement `with the lother pinion, and a pair of gearI elements adapted for engine shaft mounting in a positionthereon for operative engagement of each gear element withy the free portion of` one of said pinions,fsaid gearelements each being of a mutilatedl character providinga plurality of sets-of teeth thereon, and being relatively angular-ly arranged such that eachoperatively Vengages its pinion alternately with engagement of the otherhwith its pinion, thev gear 'elements engagingthe pinion in said alternate manner a pluralityof times in each complete revolution ofthe engine shaft,

3. A mechanism of the character described adapted for'an internal combustion engine of oscillating piston type and of a character providing al pair of oppositely oscillating pistons in a cylinder, and an engine shaft spaced there- `from, the mechanism comprising a pair of pinions each oscillatablelbyone of the engine pis.- tons, said pinions being arrangedvin lapped lengagement such that a portion of each pinion is free of tooth engagement with the other pinion,

and apair of gear elements adapted for secure ment upon the engine shaft; said gear elements being positioned thereonA relative to said pinions such that eachgear element is disposed for operative engagement with the free portion of one of saidpinions, and each. of saidv gear ele.-

ments furthery being adapted for intermittent.

of; each, pinion is; free, of tooth,V engagement with the.` other pinion, and a.- pair of gear elements adapted for-,securernent upon said engine shaft in a position thereon for operativeengagement of each gear element with theb free portion of on-e of said pinions, said gear elements being of a mutiliated character and relatively arranged such that each operatively engages its pinion alternately with engagement ofthe other with its pinion.

5. A mechanism of. the character described adaptedl fory aninternalcombustion engine of oscillatingpiston typeand of ya character providing` a pair ofoppositely., oscillating pistons in a cylinder, and anengine shaft spaced therefrom, the 'mechanismbeing-provided.for translating the oscillatingmovements, of the pistons to a unidirectionalrotary movement of the engine shaft, and comprising relatively spaced pinions arranged in a common plane, means including relatively enmeshing vgear members interconnecting said pinions; actuated'by -said oppositely oscillating pistons lfor effecting correspondingly, opposite oscillation of said pinions, and a single gear element adapted for securementupon ythe engine shaft, said gear element being disposed in the plane of said pinions and being of a mutilated character adapting the same for alternate Idriven engage ment with said pinions. v

6. A mechanism of the character described adapted for an internal combustion engine of oscillating piston type and of a `character providing a pair of oppositely oscillating pistons in a cylinder, and an engine shaft spaced therefrom, the mechanism ,being provided' for translating the os!- cillating movements of the pistons to aunidirectional rotary movement of the engine shaft, and comprising a pair of pinions each oscillatable by one of the'engine pistons, sai-d pinions being arranged in lapped engagement such that a portion of each pinion is free of tooth engagement with the other pinion, a pairvof gears adapted for securement upon said engine shaft in a position thereon for operative engagement of each with the free portion of one of said pinions, said gears 

